It is believed Hinojos was the woman who first approached the home, which jump-started the incident, Holmes said.

The boy was at his home near 55th and Minton avenues with his three younger siblings on June 22 when the woman pounded on the door, police said.

The boy went upstairs and got a handgun. Fiore forced his way into the home and aimed the gun at the boy, and the boy shot him, police said.

In the past, authorities have advised residents to ignore strangers at the door, but in light of this incident and other recent home invasions, police have modified their advice.

They now say that if a stranger arrives at a home unannounced and unscheduled, residents should not open their doors.

"Tell the person, through the door, you are not interested in speaking with them," Holmes said. " If the person's behavior persists, tell them you have your telephone and you are calling the police. If the person does not leave, follow through and call for police assistance."